CHICAGO (Reuters) - Weight-loss surgery did a better job of controlling type 2 diabetes in overweight and moderately obese patients than the most advanced medical treatment for the disease, researchers said on Monday.

The study, conducted at the Cleveland Clinic and presented at the annual scientific sessions of the American College of Cardiology in Chicago, showed that patients who underwent surgery were more than three times more likely to gain control over their diabetes after one year than the group that was treated with drugs.

Uncontrolled diabetes is a major risk factor for heart problems, including heart attack.

"Within days and hours of surgery -- before there's any measurable weight loss -- we saw dramatic changes. A majority of (surgery) patients left the hospital with normal blood sugars. However, this was not as effective for people who had diabetes for many years," said Dr. Philip Schauer, director of the Bariatric and Metabolic Institute at the Cleveland Clinic, who led the clinical trial.

Shauer called the findings, which were published in the New England Journal of Medicine, "a potential paradigm change" for how some patients should be treated for diabetes.

In the study, dubbed STAMPEDE, researchers randomly assigned 150 overweight and obese patients -- three-quarters of them female -- into one of three groups.

There were two surgery groups -- laparoscopic gastric bypass, a surgery that reroutes the digestive system and allows food to bypass part of the small intestine, and sleeve gastrectomy, a procedure that reduces the stomach to about one- quarter of its original size.

The two surgery groups were compared with a third group that got the most advanced non-insulin treatment for diabetes, such as liraglutide, marketed by Novo Nordisk under the brand name Victoza.

The research was primarily funded by Johnson & Johnson's Ethicon Endo-Surgery Inc, a maker of surgical instruments used for bariatric surgery.

REACHING GOAL

The main goal of the study was to reduce blood-sugar levels as measured by a test called HbA1c, a standard tool used to determine blood-sugar control in patients known to have diabetes. The American Diabetes Association recommends an HbA1c goal of less than 7 percent.

At the start, patients in all groups had an average HbA1c level of 9 percent. The study measured how many patients achieved levels 6 percent or lower after one year.

Researchers reported that 42 percent of patients who underwent gastric bypass surgery achieved that goal, compared with 37 percent of patients who got the sleeve gastrectomy. Just 12 percent of the patients in the drug group achieved that goal.

"This study shows, in this group of patients who have poorly controlled diabetes, surgery is more effective than medication alone," Schauer said in an interview. "More doctors who treat diabetes are going to think about surgery for these patients.

"The implication is that insurance companies might need to reconsider coverage. Right now, there's a brick wall at 35," he said, referring to the BMI threshold where insurers will cover surgery.

BMI, or Body Mass Index, is a ratio of weight to height and provides a reliable indicator of body fat for most people.

About 80 percent of the 23 million Americans living with type 2 diabetes are overweight or obese.

Not surprisingly, weight loss was five times greater among those who underwent surgery than those who did not.

In a second study also published in Monday's NEJM, a team of Italian and U.S. researchers compared longer-term results of weight-loss surgery versus medication for severely obese patients with type 2 diabetes.

Dr. Geltrude Mingrone of the Universita Cattolica del Sacro Cuore in Milan, Dr. Francesco Rubino of the Weill Medical College of Cornell University in New York, and their colleagues followed 60 patients for two years.

In that time, they found, diabetes went into remission in three quarters of the gastric-bypass patients and nearly all of the patients who underwent a surgery called biliopancreatic diversion, but in none of the patients on conventional medical therapy for diabetes.